1. Field of The Invention
The present invention relates generally to an apparatus for supplying a visual information which produces selectively different images of visual information.
2. Description of The Background Art
Various types of visual information supplying apparatuses have been proposed.
One of the previously proposed visual information supplying apparatuses is applied to a large sized motor bus in which a television camera to photograph a rear view of field and its monitor television to reproduce the photographed image are mounted.
When a switch ON (or OFF) signal is input from a switching device, a control unit controls a visual image on the television monitor derived from the television camera so that the display of the image on the monitor is turned on or off. At this time, a distance display auxiliary line to indicate a pseudo or virtual distance of, e.g., a white line in a rear view of field is superimposed on the image screen of the monitor, for example, in a form of a white line segment in order to provide a depth perception of the rear field of view for a viewer.
However, in the previously proposed visual information supplying apparatus, a plane image screen of the monitor which only provides the image information is viewed in the form of a two dimensional image and the distance displaying auxiliary line is generally set with a scale mated with a road segment image. Therefore, it is difficult to provide the distance information for the viewer when a human kind image, vehicle, or some other object images is superimposed on a front scenery portion of the auxiliary line.
Particularly, on a complicated scenery wherein various objects are present, it is not easy to provide a depth of perception and distance feeling immediately for the viewer.
On the other hand, when the viewer views a front scenery of the motor bus, it is necessary to separate his viewed angle from the image screen of the monitor to transfer a line of sight toward the front portion thereof. Therefore, the viewer, i.e., a vehicle driver needs to move his head and eyes intermittently and becomes tiresome.
Then, in order to produce the distance information which is easily recognizable, a visual information supplying apparatus of a head up display type has been proposed in a Japanese Paper of Sixth Human Interface Symposium Documents (Tokyo University, Hirose, 1990).
In this Japanese Paper, the information supplying apparatus produces a computer graphic image superimposed on the front scenery. However, it is difficult to identify the computer graphic image from the produced front scenery.